1. Field of the Invention
The present invention relates to a crossover double speaker having a small speaker and a large speaker on the upper side and on the lower side thereof.
More specifically, the present invention relates to a crossover double speaker, which includes a frame with an upper portion open; a cover installed on the upper side of the frame; a yoke installed between the frame and the cover; a small speaker unit (hereinafter referred to as a “first speaker unit”) which is installed on the bottom of the yoke, and has a first magnet with a first magnetic plate provided on the top face, and a small vibration plate (hereinafter referred to as a “first vibration plate”) installed on the upper side of the flange of the yoke above the first magnet; and a large speaker unit (hereinafter referred to as a “second speaker unit”) which is installed on the outside of the yoke, and has a second magnet with a second magnetic plate provided on the bottom face, and a large vibration plate (hereinafter referred to as a “second vibration plate”) operated separately from the first vibration plate, and the sounds generated respectively from the first speaker unit and the second speaker unit are outputted in the same direction.
2. Description of the Related Art
Communication equipment such as a mobile phone like a smartphone and audio equipment such as an earphone have a speaker embedded therein, recently, a double speaker composed of two speakers has been provided to improve the quality of sound.
For example, conventional double speakers which have two speakers embedded therein are disclosed in Japanese Patent Laid-Open Publication No. S62-277000 (electroacoustic transducer), Japanese Patent Laid-Open Publication No. H11-252683 (electroacoustic transducer) Japanese Patent Laid-Open Publication No. 2003-111194 (loudspeaker and portable terminal device), Korean Patent Registration No. 10-662533 (speaker), and Korean Patent Laid-Open No. 10-2006-89937 (speaker).
Of these, the electroacoustic transducer disclosed in Japanese Patent Laid-Open Publication No. S62-277000 includes a first and second pole pieces installed at both ends of a magnet; a yoke which forms first and second magnetic gaps respectively between these pole pieces and the outer circumference thereof, and has a disk-type bottom, a cylinder portion formed integrally on the outer circumference of the bottom, and a flange extending outward from the top end of the cylinder portion; a first speaker unit which has a first vibration plate and a first voice coil of which one end is fixed to the first vibration plate and the other end portion is inserted into the first magnetic gap; and a second speaker unit which has a second vibration plate and a second voice coil of which one end is fixed to the second vibration plate and the other end portion is inserted into the second magnetic gap.
In order to form the first speaker unit having the first vibration plate on the lower side of the bottom of the yoke like above, a circular hole should be made on the bottom of the yoke to install the first voice coil, so the work is cumbersome. Further, in order to form the second speaker unit having the second vibration plate on the upper side of the flange of the yoke, the first pole piece, the magnet, and the second pole piece should be laminated one after another, so the work is cumbersome. Furthermore, since the first pole piece, the magnet, and the second pole piece are laminated one after another in the cylinder portion of the yoke, the height of the cylinder portion increases. Therefore, the whole height of the electroacoustic transducer, namely, the speaker size increases and the whole volume thereof increases.
In particular, the low-pitched tone generated from the second speaker unit installed on the upper side of the flange of the yoke is dampened in the process of passing through between the cylinder portion with a high height and the inside of the housing. Therefore, a phenomenon of sound (output) reduction occurs. Further, since the second vibration plate of the second speaker unit and the first vibration plate of the first speaker unit are operated by the magnet installed singly, the capacity of the magnet should be increased. Therefore, the height of the electroacoustic transducer, namely, the speaker size increases and volume thereof increases. On the other hand, if the size (thickness) of the magnet is made smaller (thinner) in order to reduce the height and volume of the speaker, output of the audio equipment is lowered.
The electroacoustic transducer disclosed in Japanese Patent Laid-Open Publication No. H11-252683 includes a first speaker unit having a first vibration plate and a second speaker unit having a second vibration plate, a magnetic circuit having a magnet, a yoke, and a voice coil provided in a first magnetic gap, such that a vibration plate is driven by the operation of the magnetic circuit and the voice coil, wherein one magnetic circuit drives two vibration plates.
But since the first speaker unit, which has the first vibration plate on the lower side of the bottom of the yoke and on the outside of the cylinder portion, is formed, a phenomenon of the diameter of the first speaker unit increasing occurs. Therefore, the quality of sound is lowered as the deviation in speaker width with the second speaker unit decreases. Further, since there is no device installed in the cylinder portion of the yoke, space utilization in the cylinder portion is low.
Furthermore, in order to clearly distinguish the amplitude (sound) from the first speaker unit that has the diameter increased, the second speaker unit should be made larger. Therefore, the flange of the yoke widens, and the volume of the electroacoustic transducer increases. Since the second vibration plate of the second speaker unit and the first vibration plate of the first speaker unit are operated by the magnet installed singly on the outside (bottom face of the flange) of the cylinder portion, the output of audio equipment is lowered.
The loudspeaker disclosed in Japanese Patent Laid-Open Publication No. 2003-111194 and the speaker disclosed in Korean Patent Registration No. 10-662533 include a first speaker unit having a first magnet, a second speaker unit having a second magnet provided as to surround the first magnet, a yoke for linking the first magnet and the second magnet, a first voice coil, a first vibration plate connected to the first voice coil, a second vibration plate provided on the opposite side of the first magnet to the first vibration plate to be connected to the second voice coil, a first magnetic plate provided between the first vibration plate and the first magnet, and a second magnetic plate provided between the second vibration plate and the second magnet. The first voice coil is provided in a first magnetic gap between the first magnetic plate and the yoke, and the second voice coil is provided in a second magnetic gap between the second magnetic plate and the yoke.
But the first speaker unit installed on the upper side of the flange of the yoke like above and the second speaker unit installed on the lower side of the flange of the yoke have the sizes (diameters) of vibration plates equal, and there is a slight difference in the diameter of the voice coil installed in each vibration plate. Therefore, the amplitude of the tone (sound) generated from each vibration plate becomes almost the same, so it is not possible to clearly distinguish between high-pitched tones and low-pitched tones. Further, since the sounds generated from the respective speaker units installed on the upper side and lower side of the yoke are outputted in the respective directions (both sides), the size of the housing becomes larger.
The speaker disclosed in the Korean Patent Laid-Open Publication No. 10-2006-89937 includes a frame with the upper portion open, a yoke which is integrally joined to the lower side of the frame and inside which is formed a ring-type partition, a cap which is joined to the upper side of the frame and in which a flow hole is formed, an internal magnet installed on the inner side of the ring-type partition, an external magnet installed on the outside of the ring-type partition, a second ring-type external magnet, and a vibration plate which is installed on the upper side of the yoke and is formed integrally in the frame. The bottom face of the vibration plate is fixed to the ring-type partition by a vibration plate support, so the vibration plate is divided into an internal vibration plate and an external vibration plate. On the bottom faces of the internal vibration plate and the external vibration plate are installed respectively an internal voice coil and an external voice coil.
But the above speaker is divided by the vibration plate support, and the sounds (vibrations) generated from the integrally formed internal vibration plate and the external vibration plate are transmitted to each other to cause vibrational interference. Therefore, the sound outputted from the speaker unit is dampened, so the quality of sound is remarkably lowered. Since the sounds (vibrations) generated from the internal vibration plate and the external vibration plate are mixed and outputted in the same direction, the quality of sound decreases and the output of the audio equipment is lowered.